Ask the user to input a sequence of numbers. Then calculate the mean and print the result. Here is the solution. user_input = input('Please enter a number type exit to stop:> ') numbers = [] while user_input.lower() != 'exit': while not user_input.isdigit(): print('That is not a number! Numbers only please:> ') user_input = input('Try again:> ') numbers.append(int(user_input)) user_input = input('Please enter next number:> ') total = 0 for number in numbers: total += number print(f'Mean is {total/len(numbers)}') print(sum(numbers)/len(numbers)) Now, my goal is to attempt the question using the following logic and with slight modification to the above code. collect the numbers from the user store them one by one in a NumPy append them one by one in a NumPy array. use the np.ndarray.mean to get the mean modification to above solution import numpy as np user_nums = np.array([]) user_input = input('Please enter a number type exit to stop:> ') while user_input.lower() != 'exit': while not user_input.isdigit(): print('That is not a number! Numbers only please:> ') user_input = input('Try again:> ') np.append(user_nums,float(user_input)) # append user input to user_nums mean = user_nums.mean() print("mean is ",mean) After inputting the first number, the program takes forever to continue running leaving me no choice but to force-close the program. Can you identify my mistakes? Thanks for your kind assistance in advance.

Hey Carlton, Thank you for your question! I have commented your code below: What you need to do in order to avoid entering an infinite loop is to add a line of code asking the user for another number, like so: This time, however, we hit another issue - the mean is nan. This suggests that there is nothing stored in the user_nums variable. You can convince yourself that if you add a line of code that prints the array every time a number should be appended: In the documentation of the append() method, you will find that the method appends the value to a copy of the original array. Therefore, the method creates a copy, stores the value 1.0 there, and leaves the original array unmodified. To populate the original array, you would need to modify the code as follows: Now that works as expected! :) One should always be extra carful with while-loops. Hope this helps! Keep up the good work! Kind regards, 365 Hristina

@Hristina. Phenomenally well explained. Lessons learned from your correction np. append() does not change the original array. (This is also a reminder for me to use py docs regularly) extra care must be given when working with while loops i.e ensure that the failure condition of the loop is met.